Phenotype Frequencies of Autosomal Minor Histocompatibility Antigens Display Significant Differences among Populations

Minor histocompatibility (H) antigens are allogeneic target molecules having significant roles in alloimmune responses after human leukocyte antigen–matched solid organ and stem cell transplantation (SCT). Minor H antigens are instrumental in the processes of transplant rejection, graft-versus-host disease, and in the curative graft-versus-tumor effect of SCT. The latter characteristic enabled the current application of selected minor H antigens in clinical immunotherapeutic SCT protocols. No information exists on the global phenotypic distribution of the currently identified minor H antigens. Therefore, an estimation of their overall impact in human leukocyte antigen–matched solid organ and SCT in the major ethnic populations is still lacking. For the first time, a worldwide phenotype frequency analysis of ten autosomal minor H antigens was executed by 31 laboratories and comprised 2,685 randomly selected individuals from six major ethnic populations. Significant differences in minor H antigen frequencies were observed between the ethnic populations, some of which appeared to be geographically correlated

Case Report - HLA Chimerism in allogenic haplo-identical peripheral blood stem cell transplant

HLA antigens were used as markers to establish the presence of chimerism (i.e. simultaneous presence of two lymphocyte populations from recipient as well as donor) in a patient with chronic granulomatous disease treated with one haplotype matched stem cell transplant. Neutrophil engraftment occurred on Day 6 post peripheral blood stem cell transplant (PBSCT). Platelet counts were maintained above 20x10[9]/L. Six months after the allogenic PBSCT, lymphocyte population was chimeric and cells of both donor (father) and host HLA type were present. The patient revealed a shift in his HLA antigen profile and there was evidence of donor cell engraftment. The HLA phenotype A26,CwXX,B8,DRB1*03//A32,Cw4,B35,DRB1*16// represented his true phenotype whereas A11,Cw7,B62,DRB1*14 represented donor (father) origin.. HLA system as a genetic marker is a useful additional approach to determine engraftment following an allogenic haplo-identical stem cell transplantation